Currently, a wide variety of devices are used for depositing seeds, fertilizer and other materials in trenches and furrows formed in the ground by disk type opener and planting units, under a wide variety of soil, tillage and moisture conditions. Such varying conditions include rocky soil conditions, lightly tilled conditions wherein large dirt clods and some intact plant residue is present, and minimum till conditions wherein standing weeds, remaining plant structure, and other trash and debris are present. Under all of the above discussed conditions items such as rocks, dirt clods, and plant residues encountered in the furrow can operate to urge the material deposition apparatus of the planting unit away from the disk so as to interfere with the operability thereof to place material such as seed, fertilizer and the like in a desired position in the furrow. Additionally, in many instances the material deposition apparatus serves as a scraper for removing mud and other material from the disk, and when spaced from the disk, is not operable to perform that function. Still further, the rocks, dirt clods, plant residue, soil and other debris can become lodged between the disk and the material deposition apparatus when spaced therefrom, thereby requiring stoppage of the planting operation for removal.
To mitigate the above discussed problems, many known planting units and openers utilize a spring or other resilient biasing member to urge the material deposition apparatus against the disk. However, it has been found that dirt, dust, plant matter and the like can accumulate on, in and around such springs and other biasing members thereby interfering with their operation, as well as the operation of the material deposition apparatus itself. Such springs and other biasing members can also break and be lost.
One attempted solution to this problem has been to increase the force applied by the spring or other biasing member to urge the material deposition apparatus against the disk. However, it has been found that when such greater forces are used, the material deposition apparatus can operate like a brake to slow and even stop the rotation of the disk resulting in a plowing effect instead of the desired opening. Higher forces can also result in faster wear of the portions of the material deposition apparatus in frictional contact with the disk and the disk itself.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.